This invention relates to an extremely low frequency communications system which is integrated with a high voltage direct current power transmission system.
Over the past several years, extensive research and development effort has been directed towards the design of a reliable and survivable extremely low frequency (ELF) communications system. The implementation of such a system of low frequency operation in the range of 30-100 Hz with its unique capabilities to penetrate ocean depths for communication between a shore station and submarines located anywhere in the oceans of the world ranks high in the list of priorities for our national defense.
Because of very high implementation costs and concern over environmental issues more attention has recently been directed to consideration of surface installed designs rather than buried installations. The relaxation of the survivability requirements has opened the way for many system cost reductions. However, even those systems that are currently being considered use previously designed subsystems that are still prohibitively high in cost. It is therefore unlikely that a real breakthrough in the high cost can be achieved unless there is a radical departure from system concepts heretofore proposed.